JP2001285933A - Method for conveying measurement information in communication network and between communication systems - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication network and a communication method by which a mobile switching center(MSC) can discriminate an optimum object on the basis of all measurements generated by a mobile station(MS) in the communication network. SOLUTION: This invention provides the communication network 10 and the communication method by which measurement information as to a multiplex pilot of an object frequency is moved to realize the compatibility between communication systems 12a and 12b. The communication systems 12a and 12b have mobile switching centers(MSC) 30, 40, base stations(BS) 20 and mobile stations(MS). The mobile switching centers(MSC) 30, 40 utilize a cross-system having a signal system message. The signal system message includes configuration parameters capable of conveying the measurement information as to the multiplex pilot of the object frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of transferring measurement information between communication networks and communication systems, and more particularly to an inter-system hard handoff between communication systems.

[0002]

2. Description of the Related Art In today's wireless communication systems, a mobile station (MS) can move within an effective area of a cell or a base station (BS). As any MS moves out of the coverage area of any BS, the connection between that MS and its serving BS becomes less robust or of poor quality. When this happens, to assess whether to reselect a particular BS to be served (in idle mode) or to handoff to a neighboring BS (in busy mode) Then, the signal strength of a plurality of neighboring BSs must be measured.

[0003] Prior to handing off the MS, the serving BS requests a handoff from the serving mobile switching center (MSC), which has an effective signal strength sufficient to satisfy the handoff request. A nearby BS. Signal strength measurements are made at both the serving BS and the neighbor BS with which the MS is communicating,
Determines whether the MS should handoff, and if so, its neighboring BSs
The measurements are compared by the MSC to handoff to

[0004] The industry standard between MS and BS in CDMA is the air interface standard I / O.
Defined in S-95-B. This standard has led to a new capability of Mobile Assisted Hard Handoff (MAHHO). This capability allows the serving BS to perform other pilot strength measurements on the target frequency in addition to the pilot strength measurement of the BS currently serving.
To be able to request.

[0005] A target frequency as used herein means a frequency desired by a corresponding base station, at which measurement is made. The request by the serving BS to perform a pilot strength measurement can be made as a single request or as a request that results in a periodic measurement every hour. In each case, the MS responds to measurements for various applicable pilots on the frequency of interest.

[0006] Such measurements are sent to the serving BS and passed to the target BS during the handoff process.
The target BS used herein refers to the BS used by the MS after the handoff is completed. The target BS can identify a free or idle channel for hard handoff based on the pilot strength measurements received by the MS.

When the MS moves out of the coverage area of the communication system, an inter-system hard handoff (or handoff between communication systems) is required. Intersystem signaling standards for signals sent between the serving MSC and the target MSC are defined in TIA (Electrical Communications Association) / EIA (Electronics Industries Association) -41-D.

[0008]

During an inter-system hard handoff, only a single instance of the pilot strength measurement information is sent to the facility directive 2, handoff back2, and handoff call message to third2. In TIA / EIA-
It is transported to the target MSC as a 41-D standard. TI
The A / EIA-41-D standard does not support transmission of information for multiple pilots of MS measurements of the frequency of interest.

[0009] It would be advantageous to have a communication network and method capable of moving measurement information between a serving MSC and a target MSC communication system for multiple pilots of a target frequency. According to such networks and methods, the target MSC can determine the best target based on all measurements made by the MS.

[0010]

SUMMARY OF THE INVENTION The present invention is a communication network capable of transferring measurement information for multiple pilots of a target frequency between communication systems. The communication network includes a plurality of communication networks each having a plurality of MSCs connected to a plurality of BSs. The communication network further comprises a plurality of MSs capable of communicating with the MSC via the BS.

[0011] The plurality of MSCs comprises an intersystem communication protocol and communicates information about interoperability between the plurality of communication systems. The communication protocol of the inter-system includes a plurality of signaling messages, wherein the signaling messages include a plurality of modified parameters. The modified parameters include configuration parameters having multiple individual parameters capable of moving measurement information for multiple pilots of the frequency of interest. With these parameters, the target MSC can determine the best target to receive the handoff. The discrimination is made based on a more understandable set of measurement information compared to the prior art, which moved measurement information for only a single pilot.

The present invention provides a method for moving measurement information between communication systems. The method comprises the steps of formatting a plurality of signaling messages and a plurality of message parameters to include configuration parameters for carrying measurement information for multiple pilots of a frequency of interest, and transmitting the signaling messages between the communication systems. Steps.

The present invention applies to CDMA wireless communication systems, but includes TDMA, GSM, UMTS, and IMT-
It can be extended to other access technology systems as well as 2000.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a network and method capable of moving measurement information for multiple pilots of a frequency of interest between communication systems, providing improved handoff capabilities. The invention relates to TDMA,
Although applicable to GSM, UMTS, and IMT-2000 as well as other access technology systems, the example embodiments described therein are directed to a CDMA wireless communication system compliant with the TIA / EIA-41-D industry standard. Is disclosed.

FIG. 1 shows a communication network 10 according to the present invention.
It is a figure which shows a part of. The representation of FIG. 1 is for illustration and does not limit the possible embodiments of the network and method of the present invention. As shown in FIG. 1, one given area is served by a plurality of base stations (or cells) 20. Boundary 11 divides network 10 into two systems 12a and 12b. System 12
a and 12b are mobile switching centers (MSCs) 40 and 5 respectively.
0 respectively.

As is well known, each BS 20
It includes a transmitter, a receiver, a signal strength receiver, and a base station controller (all not shown). MSC30 and 4
0 are connected to each other and at each service area to the base station 20 by a microwave link, optical fiber, copper wire, or other well-known or used means.

A plurality of mobile stations (MS) (not shown)
Can be found in S. Each MS has one BS
From one BS to another BS, or from one communication network served by an MSC to another similar system served by another MSC. When an MS moves out of the coverage area of a BS, the signal strength of neighboring BSs is measured,
Assess whether the BS should reselect a particular neighbor BS to receive service or handoff to a neighbor BS.

1 for identifying when to initiate a handoff
One method is Mobile Assisted Hard Handoff (MAHHO), which uses the capabilities introduced in the IS-95-B communication protocol. MAHHO allows the serving BS to request the MS to perform other pilot strength measurements at the frequency of interest as well as the pilot strength measurement of the BS currently serving.

The serving BS can make this request as a one-time request or as a request that results in a periodic measurement every hour. In each case, the MS responds to measurements for various applicable pilots on the frequency of interest. These are sent to the serving BS. The BS passes them on to the target BS. The target BS may assign a channel during a hard handoff based on the measurements of the MS.

In a network using MAHHO, the MS sends a signal to a neighboring B where the signal strength to be measured is obtained.
A neighbor list identifying S is received on a dedicated channel. The MS measures the signal quality of the connection by measuring the bit error rate and the received signal strength on its assigned traffic channel. The MS also measures the pilot signal strength at neighboring BSs indicated in the measurement order from the serving base station.

The measurement order includes a pilot that the measurements need to be made at neighboring BSs. Thus, the pilots are ranked according to the signal strength received at the MS. These signal strength measurements are used to assist the target MSC in making handoff decisions and to identify the best target BS for handoff.

The serving BS receives signal quality messages from its neighbor BSs from the MS and compares each other's pilots. The BS considers the received signal strength and propagation path loss to determine whether to send an optimal pilot and handoff request to the MSC.

By using the TIA / EIA-41-D inter-system protocol, the messages carry information between the communication networks about the handoff of the call. These messages include a facility directive 2 (FacDir2) message, a band-off back (HandBack2) message, and a handoff to a third party (HandTird2) message.

According to an embodiment of the present invention, during a handoff between communication systems, measurement information for multiplexed pilots of the target frequency is transmitted from the serving BS to the serving M
It is sent to the SC and further to the target MSC. This allows the target MSC to determine the optimal target BS for handoff using all available signal strength information.

By modifying the TIA / EIA-41-D intersystem protocol, the present invention defines new configuration parameters. The configuration parameters include at least one mandatory parameter and optionally a plurality of additional parameters. The required parameter and the plurality of additional parameters include measurement information about the pilot of the target frequency. Configuration parameters are TIA / EIA
By complying with the -41-D intersystem protocol, the signaling message can carry measurement information for multiple pilots of the frequency of interest.

FIG. 2 shows a signaling message according to the conventional TIA / EIA-41-D inter-system protocol. Each message 50 is made up of a number of message parameters 60, such as CDMA channel data parameters 51. Each message parameter further includes a number element or field 52 (ie, C
For the DMA channel data parameter 51, the field 52 is composed of a CDMA channel number field, a frame offset field, and a band class field. According to the TIA / EIA-41-D standard, each message parameter is classified as either mandatory or optional.

In one embodiment of the present invention, as shown in FIG. 3, the CDMA channel data parameters of the signaling message 70 are shown as configuration parameters 71 (in FIG. 3 as CDMA channel data list parameters). ). Configuration parameter 7
1 comprises a plurality of parameters 72, each carrying measurement information about a pilot of the target frequency, such as, for example, CDMA channel data parameters.

It is desirable that one of the parameters 72 is an essential parameter and the other is an optional parameter. Each of the parameters 72 further comprises a number element or field 73. Attaching the configuration parameters provides a solution that can carry measurement information for multiple pilots of the frequency of interest. Replacing the CDMA channel data parameters with configuration parameters capable of carrying measurement information for multiple pilots provides the ability to move more transparent measurement information from one communication system to another. This allows the target system to further determine the best BS to receive the handoff based on the available measurement information.

The handoff forward, which is the handoff of the MS from the anchor / serving MSC to the target MSC, the handoff back, which returns the MS handoff from the serving MSC to the anchor MSC, and the serving M
An example of a handoff from an SC to a target MSC to a third party will be described. In the example, TIA / EIA-4
Reference is made to a communication system using signaling messages according to the 1-D intersystem protocol.

FIG. 4 is a signaling diagram according to the present invention.
The target MSC1 from the anchor and the corresponding MSC101
5 shows the message flow during the MS handoff to H.05. This process is referred to herein as handoff forward.

The handoff forward process begins when the serving MSC 101 attempts to determine, based on an internal algorithm, whether an adjacent target MSC is appropriate for handoff. The internal algorithm of the MSC determines the radio frequency (RF) propagation characteristics of the area on the specific region where the MSC is located.

If it is determined that handoff is necessary, the corresponding MSC 101 shifts to a process of transmitting a facility directive 2 (FACDIR2) paging message 122 to the target MSC 105, and
To start a handoff. FAC
The DIR2 paging message 122 includes the configuration parameters of the present invention capable of carrying measurement information for multiple pilots of the frequency of interest.

The target MSC 105 initiates a handoff and sends a FACDIR2 return result message 123 to the serving MSC. The channel selected by the target MSC is indicated therein. The target MSC selects a channel based on the measurement information contained in the configuration parameters in the previously received FACDIR2 paging message.

FACDIR2 return result message 123
Is received, the serving MSC issues a handoff command 124
To the serving MS to indicate the selected channel to which the MS should return as part of the handoff process. M
If S has completed recovery and received on the selected channel (shown at 125 in FIG. 4), the target M
The SC completes the route between the channel and the internal MSC trunk and sends an MS On Channel (MSONCH) paging message 126 to the serving MSC 101 to send the target MSC.
Notifies that C has successfully completed the handoff. The serving MSC 101 sends the MSONCH paging message 12
6, the handoff process ends.

FIG. 5 is a signaling diagram according to the invention.
An anchor and target MSC2 from the serving MSC 205
FIG. 11 shows the message flow during the handoff back of the MS to 01. This process is referred to herein as handoff back.

The start of the handoff / back process is based on whether the corresponding MSC 205 is suitable for handing back the adjacent target MSC based on an internal algorithm in the same manner as the handoff / forward process described above. Is to be determined. MSC20 in action
5 shifts to the process of transmitting the HANDBACK2 call message 222 to the anchor and the target MSC 201, and instructs the target MSC to start handoff / back. HANDBACK2 call message 222
Include the configuration parameters of the present invention that are capable of carrying measurement information for multiple pilots of the frequency of interest.

If the channel at the designated BS is valid, the anchor and target MSC 201 initiates a handoff back and sends a HANDBACK2 return result message 223 to the serving MSC 205. The channel selected by the anchor and target MSC 201 is indicated therein. The target MSC is the previously received H
The channel is selected based on the measurement information included in the configuration parameter in the ANDBACK2 paging message.

Upon receiving the HANDBACK2 return result message 223, the serving MSC sends a handoff command 224 to the serving MS 210. When the MS has completed recovery and received on the specified channel (FIG. 5)
225), the anchor and target MSC 201 sends a FACREL paging message 226 to the serving MSC 205 to indicate that the handoff has been successfully completed. The MSC 205 that is being supported is FAC
A REL return message 227 is sent to the target MSC 201. The handoff / back processing ends here.

FIG. 6 is a signaling diagram according to the present invention.
MS from serving MSC 305 to target MSC 310
5 shows the message flow during the handoff / back-up of FIG. This process is referred to herein as handoff to a third party.

The handoff process to a third party begins when:
This is the time when the serving MSC 305 attempts to determine whether the neighboring target MSC is appropriate for handoff based on an internal algorithm as in the handoff forwarding process described above. The MSC 305 currently being supported is
HANDTOTHIRD2 is assigned to the MSC that previously handed off the call to itself, that is, the MSC 301 of the anchor.
Send a paging message 322 to send the anchor MSC 3
Request 01 to perform a handoff. HAND
The TOTHIRD2 paging message contains the configuration parameters of the present invention capable of carrying measurement information for multiple pilots of the frequency of interest.

The target MSC 310 is the anchor MSC 3
01 and if the inter-MSC trunk is active, the anchor MSC 301 attempts to perform a handoff. MSC301 of anchor is FA
CDIR2 paging message 323 to target MSC 310
Send to FACDIR2 call message 323 is also
Includes configuration parameters of the present invention capable of carrying measurement information for multiple pilots of the frequency of interest. If the channel of the specified target cell is valid, the target MSC 310 initiates a handoff forward and returns a FACDIR2 return result message 324.
To the requesting MSC 301.

The MSC 301 of the anchor is HANDTH
In the IRD2 return result message 325, the selected parameter is returned to the corresponding MSC 305. Upon receiving the HANDHIRD2 return result message 325, the serving MSC 305 sends a handoff command 326 to the serving MS 315. If the MS 315 is received on the designated channel (indicated at 327 in FIG. 6), the target MSC 310 completes the path between that channel and the inter-MSC trunk, and
A paging message 328 is sent to the anchor MSC 301 to indicate that the target MSC 310 has successfully completed the handoff forward.

The anchor MSC 301 is the target MSC.
The call path is connected to the inter-MSC trunk to 310, requesting the release of the inter-MSC trunk to the previously serving MSC 305, and signaling the completion of the handoff by sending a FACREL paging message 329.
The previously serving MSC 305 idles the inter-MSC trunk and places a FACREL return result message 3
30 to the anchor MSC 301. The handoff ends here.

As described above, a communication network according to one embodiment of the present invention comprises a plurality of mobile switching centers (MSs).
C), multiple base stations (BS), and multiple mobile stations (M
S). Each MS is connected to multiple BSs. Each MS has the ability to communicate with multiple MSCs via the base station.

The plurality of MSCs communicate using an inter-system communication protocol that realizes interoperability among the plurality of MSCs. The inter-system communication protocol has a plurality of signaling messages, including a plurality of modified message parameters. Signaling messages are sent between MSCs during inter-system handoff. The signaling message is TIA / EIA-41-D
Messages, facility directive 2 messages, handoff back 2 messages, and handoff to third parties messages.

The plurality of modified message parameters include configuration parameters that have measurement information for multiple pilots of the frequency of interest. Preferably, the configuration parameters optionally include at least one mandatory parameter including measurement information for multiple pilots of the frequency of interest and a plurality of additional parameters.

According to another aspect, the invention is a method for moving measurement information between communication systems. The method comprises the steps of: formatting a plurality of signaling messages of an inter-system communication protocol to include configuration parameters capable of moving measurement information for multiple pilots of a frequency of interest; and transmitting the signaling messages between the communication systems. And transmitting. Preferably, the configuration parameters have at least one mandatory parameter and optionally a plurality of additional parameters. Each of the required parameter and the plurality of additional parameters includes measurement information for the multiplex pilot of the target frequency.

The method can be applied to TIA / EIA-41 signaling to provide the ability to move measurement information for multiple pilots of the frequency of interest between communication systems.

[Brief description of the drawings]

FIG. 1 shows a part of a communication network according to the invention.

FIG. 2 is a diagram showing a signaling message according to a communication protocol of a conventional mutual system.

FIG. 3 illustrates a signaling message according to one embodiment of the invention.

FIG. 4 is a signaling diagram illustrating message flow during an inter-system handoff forward according to one embodiment of the present invention.

FIG. 5 is a signaling diagram illustrating message flow during an inter-system handoff back according to one embodiment of the present invention.

FIG. 6 is a signaling diagram illustrating message flow during a handoff of an inter-system to a third party according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Communication network 11 Boundary line 12a, 12b Communication system 20 Base station 30, 40 Mobile switching center 50 Conventional signaling message 51 CDMA channel data parameter in signaling message 50 52 Field in signaling message 50 60 in signaling message 50 Message Parameters 70 Signaling Message 71 of the Present Invention 71 Configuration Parameters in Signaling Message 70 72 Plurality of Parameters in Signaling Message 70 73 Fields 101, 201 in Signaling Message 70 Anchor / Corresponding Mobile Switching Center 105, 310 Target Movement Switching stations 110, 210, 315 Mobile stations 122, 126, 222, 226, 322, 323, 3
28,329 paging message 123,223,227,324,325,330 Return result message 124,224,326 Command message 205,305

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 596077259 600 Mountain Avenue, Murray Hill, New Jersey 07974-0636 U.S.A. S. A.

Claims (8)

[Claims] 1. A) a plurality of base stations (BS); and B) a modification connected to each of the plurality of BSs, and including configuration parameters capable of moving measurement information for multiplexed pilots of a frequency of interest. A plurality of mobile switching centers (MSCs) communicating between each other using an inter-system communication protocol that achieves interoperability with signaling messages having message parameters; C) communicating with the MSCs via the BS. A communication network comprising a plurality of communication systems including a plurality of mobile stations (MS) each having a capability. 2. The communication system according to claim 2, wherein
The communication network according to claim 1, wherein the communication network conforms to the IA / EIA-41 signaling standard. 3. The configuration parameter according to claim 1, wherein the configuration parameter includes a required parameter and an optional additional parameter, wherein each of the required parameter and the additional parameter includes measurement information on a multiplexed pilot of a target frequency. Communication network as described. 4. The system of claim 1, wherein the plurality of signaling messages in the communication system are transmitted from a serving MSC to a target MSC during an inter-system hard handoff. Communication network. 5. The method according to claim 1, wherein the plurality of signaling messages in the communication system include a facility directive 2
The communication network of claim 1, comprising a paging message, a handoff back 2 paging message, and a handoff paging message to a third party. 6. A) formatting a signaling message of an inter-system communication protocol to include configuration parameters capable of moving measurement information for multiple pilots of the frequency of interest; and B) signaling the signal between communication systems. Transmitting the measurement information between the communication systems. 7. The method according to claim 1, wherein the step (A) is performed by TIA / EIA.
7. The method of transferring measurement information between communication systems according to claim 6, wherein the method is applied to a -41 signaling standard. 8. The method of claim 1, wherein the configuration parameter includes a required parameter and an optional additional parameter, wherein each of the required parameter and the additional parameter includes measurement information on a multiplexed pilot of a target frequency. 7. The method for moving measurement information between communication systems according to claim 6.